[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Australian spinosaur ref and other new papers

From: Ben Creisler

This find was mentioned already in news stories but the paper is now
available officially:

Paul M. Barrett, Roger B. J. Benson, Thomas H. Rich, and Patricia
Vickers-Rich (2011)
First spinosaurid dinosaur from Australia and the cosmopolitanism of
Cretaceous dinosaur faunas.
Biology Letters (advance online publication)
Published online before print June 21, 2011, 
doi: 10.1098/rsbl.2011.0466 

A cervical vertebra from the Early Cretaceous of Victoria represents the
first Australian spinosaurid theropod dinosaur. This discovery
significantly extends the geographical range of spinosaurids, suggesting
that the clade obtained a near-global distribution before the onset of
Pangaean fragmentation. The combined presence of spinosaurid, neovenatorid,
tyrannosauroid and dromaeosaurid theropods in the Australian Cretaceous
undermines previous suggestions that the dinosaur fauna of this region was
either largely endemic or predominantly ?Gondwanan? in composition. Many
lineages are well-represented in both Laurasia and Gondwana, and these
observations suggest that Early-?middle? Cretaceous theropod clades
possessed more cosmopolitan distributions than assumed previously, and that
caution is necessary when attempting to establish palaeobiogeographic
patterns on the basis of a patchily distributed fossil record. 

Federico L. Agnolin and Fernando E. Novas (2011)
A carpometacarpus from the Upper Cretaceous of Patagonia sheds light on the
Ornithurine bird radiation. 
Paläontologische Zeitschrift (advance online publication)
DOI: 10.1007/s12542-011-0112-2 

We report the discovery of an isolated avian carpometacarpus from the Upper
Cretaceous Allen Formation (Campanian-Maastrichtian), Salitral Moreno, Río
Negro Province, Argentina. This specimen is referred to cf. Neornithes
because it presents a distinct but shallow infratrochlear fossa, a
shortened ventral rim of the carpal trochlea that does not contact the base
of the extensor process, and an extensor process conspicuously surpassing
cranially the articular facet for digit I. The isolated nature of the
specimen precludes its inclusion within the main neornithine lineages.
Although it may represent part of the crown clade Neornithes, the limited
data available do not confidently support placement within any particular
lineage. The carpometacarpus constitutes one of the few records of Mesozoic
Neornithine-like birds for South America. 

The pdf is free for this one:

Jason R. Ali & David W. Krause
Late Cretaceous bioconnections between Indo-Madagascar and Antarctica:
refutation of the Gunnerus Ridge causeway hypothesis.
Journal of Biogeography (advance online publication)
DOI: 10.1111/j.1365-2699.2011.02546.x

Aim To evaluate the Gunnerus Ridge land-bridge hypothesis, which postulates
a Late Cretaceous causeway between eastern Antarctica and southern
Madagascar allowing the passage of terrestrial vertebrates.

Location Eastern Antarctica, southern Indian Ocean, Madagascar.

Methods The review involves palaeogeographical modelling, which draws upon
geological and geophysical data, bathymetric charts, and plate tectonic
reconstructions, and the evaluation of stratigraphically calibrated
phylogenetic analyses to document ghost lineages of select taxa.

Results The available geological and geophysical evidence indicates that
eastern Antarctica?s Gunnerus Ridge and southern Madagascar were separated
for the entire Late Cretaceous by a vast marine expanse. In the mid?Late
Cretaceous, the gap was probably punctuated by land on two intervening
physiographical highs, the northern Madagascar Plateau and Conrad Rise, the
latter of which, although probably large, was still separated from
Antarctica?s Riiser-Larsen Peninsula by c. 1600 km. Recent,
stratigraphically calibrated phylogenies including large, terrestrial
end-Cretaceous vertebrate taxa of Madagascar and the Indian subcontinent
reveal long ghost lineages that extended into the Early Cretaceous.

Main conclusions The view that Antarctica and Madagascar were connected by
a long causeway between the Gunnerus Ridge and southern Madagascar in the
Late Cretaceous, and that terrestrial vertebrates were able to colonize new
frontiers using this physiographical feature, is almost certainly
incorrect, as was previously demonstrated for the purported causeway
between Antarctica and the Indian subcontinent across the Kerguelen
Plateau. Connection across mainland Africa to account for the close
relationships of several fossil and extant vertebrate taxa of
Indo-Madagascar and South America is another option, although this too
lacks credibility. We conclude that (1) throughout the Late Cretaceous
there was no intervening, continuous causeway through Antarctica and
associated land bridges between South America to the west and
Indo-Madagascar to the east; and (2) mid- to large-sized, obligate
terrestrial forms (e.g. abelisauroid theropod and titanosaurian sauropod
dinosaurs and notosuchian crocodyliforms) gained broad distribution across
Gondwanan land masses prior to fragmentation and were isolated on
Indo-Madagascar before the end of the Early Cretaceous.

Genise,J. F. and SarzettI, L. C. (2011)
Fossil cocoons associated with a dinosaur egg from Patagonia, Argentina. 
Palaeontology (advance online publication) 
doi: 10.1111/j.1475-4983.2011.01064.x

Eight fossil (Cretaceous) insect cocoons were discovered within the
infillings of a broken dinosaur egg of a clutch from a Patagonian locality.
Cocoons are considered to be in situ based on detailed preservation of
thin, delicate walls with surface texture, infillings that are similar to
the surrounding rock matrix and the clustered distribution of cocoons in
only one egg out of the clutch of five eggs. According to the shape, size,
and thin wall with surface texture, the cocoons are interpreted as having
been produced by wasps. The wasps may have been attracted to the egg
because of the presence of scavenging insects feeding on the decaying
organic matter, or they may have been attracted to spiders feeding on the
scavenging insects. In either scenario, after attacking the insects or
spiders inside the sand infillings of the egg, the wasp larvae produced the
cocoons described herein. The presence of wasps, which are at the top of
the scavenging food webs, suggests that a complex community of
invertebrates would have developed around rotten dinosaur eggs.

A bit more info on this major new paper (already announced on the DML) with
free supps link:

Cristiano Dal Sasso & Simone Maganuco (2011)
Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous
of Italy. 
Memorie della Società italiana di Scienze naturali e del Museo civico di
Storia naturale di Milano
 37 (2011) 282 pp.

mail2web.com - Microsoft® Exchange solutions from a leading provider -